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Asteroid to Hit Africa!
A small asteroid was headed for a fiery but harmless dive into Earth's atmosphere early Tuesday morning over Africa, astronomers said in a first of its kind advance warning.
Harvard scientists announced late Monday afternoon that the asteroid 2008 TC3 would burn up in the sky, making a fireball potentially visible to people in northern Africa. Measuring between 3 feet and 15 feet in diameter, the rock was expected to enter Earth's atmosphere above Sudan at 4:46 p.m. Hawai'i time Monday, just before dawn in Africa.
Harvard astronomer Tim Spahr said the asteroid was so small it wouldn't reach the ground before burning up and wouldn't hurt anyone, but the fireball should be seen heading from west to east. A small asteroid was headed for a fiery but harmless dive into Earth's atmosphere early Tuesday morning over Africa, astronomers ... more -
Espansione dell’Universo, questione di punti di vista?
Mentre decine di scienziati si stanno arrovellando il cervello nel tentativo di spiegare la velocità sempre maggiore dell'espansione dell'Universo, tirando in ballo anche "energie oscure", un gruppo di ricercatori di Oxford sta tentando di provare un'altra teoria: a causa della posizione "speciale" del nostro pianeta nel cosmo, dal nostro punto di vista l'Universo sembra che si stia espandendo ma in realtà non è così. Attraverso l'osservazione di alcune Supernove si potrebbe provare questa "ardita" teoria, la quale però si scontrerebbe con il principio copernicano che posiziona la Terra intorno al Sole e che afferma che non c'è differenza tra i vari punti dello spazio cosmico.
Noi rimaniamo in attesa... Mentre decine di scienziati si stanno arrovellando il cervello nel tentativo di spiegare la velocità sempre maggiore dell'espansi... more -
Do we live in a giant cosmic bubble?
Objects in the Universe that seem far away are actually closer, if this theory is true.
If the notion of dark energy sounds improbable, get ready for an even more outlandish suggestion.
Earth may be trapped in an abnormal bubble of space-time that is particularly void of matter. Scientists say this condition could account for the apparent acceleration of the universe's expansion, for which dark energy currently is the leading explanation.
Dark energy is the name given to the hypothetical force that could be drawing all the stuff in the universe outward at an ever-increasing rate. Current thinking is that 74 percent of the universe could be made up of this exotic dark energy, with another 21 percent being dark matter, and normal matter comprising the remaining 5 percent.
Until now, there has been no good way to choose between dark energy or the void explanation, but a new study outlines a potential test of the bubble scenario.
If we were in an unusually sparse area of the universe, then things could look farther away than they really are and there would be no need to rely on dark energy as an explanation for certain astronomical observations.
"If we lived in a very large under-density, then the space-time itself wouldn't be accelerating," said researcher Timothy Clifton of Oxford University in England. "It would just be that the observations, if interpreted in the usual way, would look like they were."
Scientists first detected the acceleration by noting that distant supernovae seemed to be moving away from us faster than they should be. One type of supernova (called Type Ia) is a useful distance indicator, because the explosions always have the same intrinsic brightness. Since light gets dimmer the farther it travels, that means that when the supernovae appear faint to us, they are far away, and when they appear bright, they are closer in.
But if we happened to be in a portion of the universe with less matter in it than normal, then the space-time around us would be different than it is outside, because matter warps space-time. Light travelling from supernovae outside our bubble would appear dimmer, because the light would diverge more than we would expect once it got inside our void. Objects in the Universe that seem far away are actually closer, if this theory is true. ... more -
Hubble finds unidentified object in space, scientists puzzled
This is exactly why we send astronauts to risk their life to service Hubble: in a paper published last week in the Astrophysical Journal, scientists detail the discovery of a new unidentified object in the middle of nowhere.
I don't know about you, but when a research paper conclusion says "We suggest that the transient may be one of a new class" I get a chill of oooh-aaahness down my spine. Especially when after a hundred days of observation, it disappeared from the sky with no explanation. Get your tinfoil hats out, because it gets even weirder.
The object also appeared out of nowhere. It just wasn't there before. In fact, they don't even know where it is exactly located because it didn't behave like anything they know. Apparently, it can't be closer than 130 light-years but it can be as far as 11 billion light-years away. It's not in any known galaxy either. And they have ruled out a supernova too. It's something that they have never encountered before. In other words: they don't have a single clue about where or what the hell this thing is.
The shape of the light curve is inconsistent with microlensing. In addition to being inconsistent with all known supernova types, is not matched to any spectrum in the Sloan Digital Sky Survey database.
The only thing the astronomers—working on the Supernova Cosmology Project—can tell is that it appeared all of the sudden in the direction of a cluster with the catchy name of CL 1432.5+3332.8, about 8.2 billion light-years away. Hubble caught a spark that continued to brighten during a 100-day period, peaking at the 21st magnitude, only to fade away in the same period of time.
Apparently, one scientist at the LHC declared that the object is similar to the flash that an Imperial Star Destroyer does when reaching Warp 10. Who Knows?? This is exactly why we send astronauts to risk their life to service Hubble: in a paper published last week in the Astrophysical Journ... more -
Solar wind blows at 50-year low
The stream of particles which is spewed forth from the surface of the sun, rather mildly termed the solar wind, is at a 50 year low, according to scientists. The stream of particles which is spewed forth from the surface of the sun, rather mildly termed the solar wind, is at a 50 year low, a... more
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13th Astrological sign - are you reading the wrong horoscope?
Astonomers claim that Astrologers are using an outdated zodiac with the twelve signs covering uneven periods and that there are actually thirteen when Ophiuchus is included. Astonomers claim that Astrologers are using an outdated zodiac with the twelve signs covering uneven periods and that there are actual... more
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Evidence points to planet collision
Masses of dust floating around a distant binary star system suggest that two Earth-like planets obliterated each other in a violent collision, US researchers reported on Friday.
"It's as if Earth and Venus collided with each other," Benjamin Zuckerman, an astronomer at the University of California Los Angeles, who worked on the study, said in a statement.
"Astronomers have never seen anything like this before; apparently major, catastrophic, collisions can take place in a fully mature planetary system."
Writing in the Astrophysical Journal, the team at UCLA, Tennessee State University and the California Institute of Technology said it spotted the dust orbiting a star known as BD +20 307, 300 million light-years from Earth in the constellation Aries.
A light-year is the distance light travels in a year, or about 6 trillion miles. So the observations are, in essence, looking back in time 300 million years.
"If any life was present on either planet, the massive collision would have wiped out everything in a matter of minutes: the ultimate extinction event," said Gregory Henry of Tennessee State University.
BD +20 307 appears to be composed of two stars, both very similar in mass, temperature and size to the Earth's sun. They spin about their common centre of mass every 3 1/2 days or so.
"The planetary collision in BD +20 307 was not observed directly but, rather, was inferred from the extraordinary quantity of dust particles that orbit the binary pair at about the same distance as Earth and Venus are from our sun," Henry said.
"If this dust does indeed point to the presence of terrestrial planets, then this represents the first known example of planets of any mass in orbit around a close binary star."
In July 2005, the team reported it had spotted the system, then believed to consist of a single star. It was surrounded by more warm orbiting dust than any other sun-like star known to astronomers.
"This poses two very interesting questions," said Tennessee State's Francis Fekel. "How do planetary orbits become destabilized in such an old, mature system? Could such a collision happen in our own solar system?" Masses of dust floating around a distant binary star system suggest that two Earth-like planets obliterated each other in a violent co... more -
Dwarf planet given Hawaiian name "Haumea"
A newly discovered dwarf planet in the solar system is being given a Hawaiian name: Haumea, the goddess of earth and fertility.
Haumea's name was approved Wednesday by the International Astronomical Union in Paris. It is the solar system's fifth dwarf planet, in the same category and region as Pluto.
Unlike other round planets, Haumea is shaped like a fat cigar or an elongated egg. Astronomers think its shape comes from its rapid rotation, which could have been caused by a collision with another object billions of years ago.
Haumea is orbited by two moons, Hiiaka and Namaka, named after two children of the goddess. The discovery of Haumea was announced in mid-2005, and it was previously known as 2003 EL61. A newly discovered dwarf planet in the solar system is being given a Hawaiian name: Haumea, the goddess of earth and fertility. ... more -
Space Nomads
About half the stars in our celestial neighborhood may have traveled great distances through the Milky Way, according to a new study, which suggests our sun may be one of them.
People have generally assumed that once a star forms inside a galactic disk, it stays in a more or less fixed orbit around the center of its galaxy, said lead study author Rok Roškar, a graduate student in astronomy at the University of Washington in Seattle.
And there's a 50-50 chance that our sun did just that, according to the simulation, which involved more than 100,000 hours of computer time.
About half the stars within 130 light-years of our sun have made such galactic voyages, the researchers determined.
(see link for rest of article) About half the stars in our celestial neighborhood may have traveled great distances through the Milky Way, according to a new study, ... more -
Fotografato il primo pianeta fuori del sistema solare
Indirettamente, tramite analisi matematiche, ne sono stati individuati moltissimi; nessuno però era riuscito a fotografarne uno direttamente. Alla Università di Toronto però sono riusciti nell'impresa grazie al telescopio "Gemini North", che si trova nelle isole Hawaii. Con una massa gassosa simile a quella di Giove e distante 500 anni luce dalla Terra, è stato possibile immortalarlo grazie alla sua orbita molto ellittica che lo porta ad allontanarsi molto dal suo sole. Nonostante sia stata rilevata la presenza di acqua e carbonio, il pianeta non è vivibile, per cui gli scienziati dovranno scrutare ancora per molto tempo il cielo alla ricerca di altri pianeti su cui trovare vita evoluta come la nostra. Indirettamente, tramite analisi matematiche, ne sono stati individuati moltissimi; nessuno però era riuscito a fotografarne uno dirett... more
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Rare upside down rainbow caught on camera
The rare spectacle of a rainbow which curves up rather than down was caught on camera at the weekend by an astronomer near her home in Cambridge.
The "smiling" band of brilliant colours is known as a circumzenithal arc. It occurs when sunlight bounces off ice crystals high in the atmosphere, sending the light rays back up towards the sky. It differs from a normal rainbow where light penetrates raindrops and re-emerges on the other side heading towards earth, causing a drooping effect.
Upside down rainbows are rarely seen outside the polar regions and need a particular set of atmospheric conditions in order to occur.
A spokeswoman for the Met Office said upside down rainbows were an unusual sight in British skies. She said: "It is convex to the sun and is formed by refraction in suitably-oriented ice crystals and may show vivid rainbow colouring, as this one does." The rare spectacle of a rainbow which curves up rather than down was caught on camera at the weekend by an astronomer near her home in... more -
Alien planet imaged directly for the first time
Astronomers have imaged what they believe is an extrasolar planet: if in fact they have, it would be the first time one has ever been observed directly. Astronomers have imaged what they believe is an extrasolar planet: if in fact they have, it would be the first time one has ever been ... more
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The end of the world, live!
If (or, when) the big asteroid hits us and takes us out of existence, it will be to the soundtrack of Pink Floyd. This is what it will look like. If (or, when) the big asteroid hits us and takes us out of existence, it will be to the soundtrack of Pink Floyd. This is what it will... more
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10 things you don't know about the Earth
From the guys at Bad Astronomy, here's a list of interesting factoids about the planet we call home (well, most of us call it home anyways). Did you know that the earth is smoother than a billiard ball, it's growing more massive by the day, and it's round but not round? From the guys at Bad Astronomy, here's a list of interesting factoids about the planet we call home (well, most of us call it hom... more
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Scientists discover object that orbits sun backwards
A University of B.C. astronomer is among an international team of scientists who have discovered an unusual object that orbits the sun backwards on a unique tilt, a find that could lead to a better understanding of how our solar system was formed. A University of B.C. astronomer is among an international team of scientists who have discovered an unusual object that orbits the sun... more
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First glimpse of our local black hole
The closest look at the gaping maw of the giant black hole that sits at the heart of our own galaxy has been taken by astronomers.
Because this remarkable object is so distant - it takes light from around the hole 25,000 years to reach Earth - they had to make among the highest resolution measurement ever achieved to reveal what, in cosmic terms, is a very small structure.
By combining telescopes in Hawaii, Arizona, and California, astronomers could make out the tiny angular scale of 37 micro-arcseconds - the equivalent of a baseball seen on the surface of the moon, that is, 240,000 miles away - to probe how the laws of physics behave in these extraordinary conditions.
The cores of most large galaxies are thought to harbour supermassive black holes - formed from the coalescence of smaller black holes, or by the accretion of stars and gas. That includes our own galaxy, the Milky Way.
**CONTINUES** The closest look at the gaping maw of the giant black hole that sits at the heart of our own galaxy has been taken by astronomers. ... more -
Billion-dollar European Probe Set for Asteroid Encounter
From the report: Far from Earth, a robot spacecraft has been prodded from deep slumber to make a rare encounter with an asteroid, the intriguing orbital debris that could offer clues into the making of the Solar System.
he pride of the European Space Agency (ESA), the probe Rosetta has been ordered out of hibernation four and a half years into a 10-year trek that will take it into the dark chill of deep space.
Rosetta is due to rendezvous in 2014 with Comet 67P/Churyumov-Gerasimenko, sending down a refrigerator-sized lab to examine its crusty surface.
But its 6.5-billion-kilometre (4.06-billion-mile) odyssey will be interrupted on Friday, when the craft will get down to some serious science as it zooms through the asteroid belt between Mars and Jupiter.
Some 360 million kilometres (225 million miles) from home, Rosetta will carry out a flip to let its array of cameras and scanners snatch what could be a stunning view of a 10-kilometer (six-mile) -long space rock called (2867) Steins.
It will aim to get unprecedented high-resolution data of Steins' shape, size and spin, and maybe also tease out clues about its density and composition.
These could add useful knowledge about how asteroids -- hypothesised as primordial rubble left from the building of the Solar System -- weather during their aeons in orbit, said Rosetta's mission manager, Gerhard Schwehm.
"It's an E-type [asteroid], which is a silicate asteroid with a dark surface, and has not been looked at before from a spacecraft," he told AFP.
And experts in monitoring space rocks that are a potential threat to Earth will also be looking closely, said Schwehm.
"There's a lot of scientific interest in asteroids as primitive objects, but there's also interest in them as hazards, as Near-Earth Objects," he said.
"It's always useful to see their different composition, shape and size. By looking at them close-up and then comparing them with ground-based data, you can see how your classification and measurement systems perform."
At the closest point, expected at 1858 GMT on Friday, the craft will flash past Steins at a distance of 800 kms (500 miles) and with a speed of 8.6 kms (5.2 miles) per second, or 30,720 kph (19,200 mph).
Rosetta is due to carry out a second asteroid flyby, skimming past a 100-km (62-mile) behemoth called 21 Lutetia in July 2010.
Costing a billion euros (1.45 billion dollars), Rosetta is the most ambitious mission ever undertaken by ESA.
The project was approved in 1993 and launched in 2004 from ESA's base at Kourou, French Guiana.
Since then, the spacecraft has looped twice around the Earth and once around Mars, using planetary gravity as a slingshot to help it build up speed.
A third gravitational "assist" by Earth is due in November 2009.
If all goes well, Rosetta will meet up with Churyumov-Gerasimenko in May 2014 and then send down a lander, known as Philae, that will anchor to the comet's surface and analyse samples in a tiny onboard lab.
Friday's flyby of asteroid Steins coincides by accident with another big date for ESA, when its truck-sized robot freighter, Jules Verne, is scheduled to detach from the orbital International Space Station (ISS) after a five-month maiden mission. From the report: Far from Earth, a robot spacecraft has been prodded from deep slumber to make a rare encounter with an asteroid, the ... more -
NASA's Carl Sagan Fellowship to Study Extraterrestrial Worlds
From the report: NASA announced Wednesday the new Carl Sagan Postdoctoral Fellowships in Exoplanet Exploration, created to inspire the next generation of explorers seeking to learn more about planets, and possibly life, around other stars.
Planets beyond our solar system, called exoplanets, are being discovered at a staggering pace, with more than 300 currently known. Decades ago, long before any exoplanets had been found, the late Carl Sagan imagined such worlds, and pioneered the scientific pursuit of life that might exist on them. Sagan was an astronomer and a highly successful science communicator.
Follow link for full article. From the report: NASA announced Wednesday the new Carl Sagan Postdoctoral Fellowships in Exoplanet Exploration, created to inspire the... more -
Cosmic crash unmasks dark matter
"Striking evidence has been found for the enigmatic "stuff" called dark matter which makes up 23% of the Universe, yet is invisible to our eyes.
The results come from astronomical observations of a titanic collision between two clusters of galaxies 5.7 billion light-years away.
Astronomers detected the dark matter because it separated from the normal matter during the cosmic smash-up.
The research team are to publish their findings in the Astrophysical Journal..." "Striking evidence has been found for the enigmatic "stuff" called dark matter which makes up 23% of the Universe, yet ... more -
Black hole star mystery 'solved'
Astronomers have shed light on how stars can form around a massive black hole, defying conventional wisdom.
Scientists have long wondered how stars develop in such extreme conditions.
Molecular clouds - the normal birth places of stars - would be ripped apart by the immense gravity, a team explains in Science magazine.
But the researchers say stars can form from elliptical discs - the relics of giant gas clouds torn apart by encounters with black holes.
They made the discovery after developing computer simulations of giant gas clouds being sucked into black holes like water spiralling down a plughole.
"These simulations show that young stars can form in the neighbourhood of supermassive black holes as long as there is a reasonable supply of massive clouds of gas from further out in the galaxy," said co-author Ian Bonnell from St Andrews University, UK.
More Information : http://sciencenow.sciencemag.org/cgi/content/full/2008/...
http://www.stfc.ac.uk/PMC/PRel/STFC/YoungStars.aspx Astronomers have shed light on how stars can form around a massive black hole, defying conventional wisdom. ... more
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